The disclosure relates to a hydraulic unit of a vehicle brake system having at least one pump element, which is driven by means of an eccentric, which is enclosed by an eccentric chamber. The disclosure further relates to a method for operating such a hydraulic unit and to use of such a hydraulic unit in a vehicle brake system.
Hydraulic units are used in vehicle brake systems, for example motor cars or trucks, in order to be able to provide a controlled brake pressure in associated brake circuits. This relates, in particular, to functions of an antilock braking system (ABS) and/or an electronic stability program (ESP). Known hydraulic units comprise a hydraulic block in the form of a block-shaped housing, in which multiple working bores are provided. The hydraulic block also serves with at least one corresponding bore as pump housing for at least one pump element, which works on the principle of a piston pump. For this purpose, the separate pump element comprises a pump piston, which by means of an eccentric is driven to perform a reciprocating translational movement in an associated pump cylinder. Moved in this way, it is possible to pump and deliver a hydraulic fluid in the form of a brake fluid, which serves to generate the brake pressure. Here the eccentric is driven by means of a shaft, which is supported in the hydraulic block and is coupled to a drive motor, transmitting the power in such a way that the shaft can be made to perform a rotational movement.
In particular, the rotational movement of the shaft and the translational movement of the separate pump piston during operation of the hydraulic unit can cause oscillations in and on the hydraulic unit. The oscillations may be transmitted to a wide variety of seals, which serve in an associated hydraulic system to seal off the hydraulic fluid from an external space surrounding the hydraulic system. Seals of the pump elements or piston pumps are particularly affected by this. This phenomenon is widely known in the field of hydraulics and is not confined to vehicle brake systems.